Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gluconeogenic conditions, such as administration of triamcinolone or alloxan diabetes, cause the following changes in the molecular structure and properties of rabbit liver fructose 1,6-bisphosphatase (D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11): (1) the appearance of traces (about 10%) of a lighter subunit; (2) loss of tryptophan from all of the subunits, including those that show no apparent change in molecular weight; (3) increase in requirement for the positive allosteric effector, histidine; (4) increase in amount of enzyme, but not its specific activity. These changes are identical to those induced by cold or fasting, and are related to increased activities of lysosomal proteases. The results suggest that lysosomes may act as mediators of gluconeogenic stimuli.
 ...
PMID:Hormonal effects on structure and catalytic properties of fructose 1,6-bisphosphatase. 17 48

A coding-length clone of rat liver fructose-1,6-bisphosphatase (EC 3.1.3.11) was isolated by immunological screening of a cDNA library in lambda gt11. Its identity was verified by comparing the deduced amino acid sequence with that obtained by direct sequencing of a complete set of CNBr and proteolytic peptides from the purified protein. The enzyme subunit is composed of 362 amino acids and has N-acetylvaline as the amino-terminal residue. The cDNA, 1255 base pairs (bp) long, consisted of 1086 bp of coding region, 15 bp of 5' untranslated sequence, and 154 bp at the 3' untranslated end. The 3' untranslated sequence contained a polyadenylylation signal (AATAAA) followed after 30 bp by a stretch of 7 adenines at the end of the clone. The deduced amino acid sequence was identical to the primary sequence of the protein and confirmed the alignment of five nonoverlapping peptides. It also confirmed the 27-residue extension, unique to the rat liver subunit, ending with a carboxyl-terminal phenylalanine. RNA blot analyses using the radiolabeled liver cDNA as a probe revealed a single band of fructose-1,6-bisphosphatase mRNA, 1.4 kilobases long, in liver and kidney but not in nongluconeogenic tissues. Fructose-1,6-bisphosphatase mRNA was increased 10-fold in livers from diabetic rats and was reduced to control levels after 24 hr of insulin treatment, suggesting that the changes in enzyme activity observed in diabetes and after insulin treatment are due to alterations in mRNA abundance.
 ...
PMID:cDNA sequence of rat liver fructose-1,6-bisphosphatase and evidence for down-regulation of its mRNA by insulin. 284 61

The level of fructose 2,6-bisphosphate (F2,6P2), a potent stimulator of 6-phosphofructo-1-kinase and inhibitor of fructose 1,6-bisphosphatase, was measured in three different muscle types (tensor fascia latae, biceps femoris, and soleus) and in the liver of normal and diabetic rats. The mean (+/- SEM) content of F2,6P2 (nanomoles per g tissue) varied among the three types of skeletal muscle in normal rats, with the biceps femoris having the highest (0.97 +/- 0.15) and the soleus the lowest (0.57 +/- 0.03) levels. However, these differences were unrelated to simultaneous estimates of skeletal muscle activity of 6-phosphofructo-1-kinase activity. The total concentration of F2,6P2 was more than 8-fold higher (8.5 +/- 0.9) in the liver, and this value fell to 5.3 +/- 0.8 (P less than 0.05) after the induction of diabetes with streptozotocin. In contrast, F2,6P2 levels did not fall in skeletal muscle of rats with streptozotocin-induced diabetes, and the concentration actually increased. Thus, the fall in hepatic F2,6P2 concentration associated with insulin deficiency was not observed in skeletal muscle.
 ...
PMID:Evidence that insulin deficiency in the rat has disparate effects on fructose 2,6-bisphosphate levels in muscle and liver. 293 40

Acute hormonal regulation of liver carbohydrate metabolism mainly involves changes in the cytosolic levels of cAMP and Ca2+. Epinephrine, acting through beta 2-adrenergic receptors, and glucagon activate adenylate cyclase in the liver plasma membrane through a mechanism involving a guanine nucleotide-binding protein that is stimulatory to the enzyme. The resulting accumulation of cAMP leads to activation of cAMP-dependent protein kinase, which, in turn, phosphorylates many intracellular enzymes involved in the regulation of glycogen metabolism, gluconeogenesis, and glycolysis. These are (1) phosphorylase b kinase, which is activated and, in turn, phosphorylates and activates phosphorylase, the rate-limiting enzyme for glycogen breakdown; (2) glycogen synthase, which is inactivated and is rate-controlling for glycogen synthesis; (3) pyruvate kinase, which is inactivated and is an important regulatory enzyme for glycolysis; and (4) the 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase bifunctional enzyme, phosphorylation of which leads to decreased formation of fructose 2,6-P2, which is an activator of 6-phosphofructo-1-kinase and an inhibitor of fructose 1,6-bisphosphatase, both of which are important regulatory enzymes for glycolysis and gluconeogenesis. In addition to rapid effects of glucagon and beta-adrenergic agonists to increase hepatic glucose output by stimulating glycogenolysis and gluconeogenesis and inhibiting glycogen synthesis and glycolysis, these agents produce longer-term stimulatory effects on gluconeogenesis through altered synthesis of certain enzymes of gluconeogenesis/glycolysis and amino acid metabolism. For example, P-enolpyruvate carboxykinase is induced through an effect at the level of transcription mediated by cAMP-dependent protein kinase. Tyrosine amino-transferase, serine dehydratase, tryptophan oxygenase, and glucokinase are also regulated by cAMP, in part at the level of specific messenger RNA synthesis. The sympathetic nervous system and its neurohumoral agonists epinephrine and norepinephrine also rapidly alter hepatic glycogen metabolism and gluconeogenesis acting through alpha 1-adrenergic receptors. The primary response to these agonists is the phosphodiesterase-mediated breakdown of the plasma membrane polyphosphoinositide phosphatidylinositol 4,5-P2 to inositol 1,4,5-P3 and 1,2-diacylglycerol. This involves a guanine nucleotide-binding protein that is different from those involved in the regulation of adenylate cyclase. Inositol 1,4,5-P3 acts as an intracellular messenger for Ca2+ mobilization by releasing Ca2+ from the endoplasmic reticulum.(ABSTRACT TRUNCATED AT 400 WORDS)
Diabetes Metab Rev 1987 Jan
PMID:Mechanisms of hormonal regulation of hepatic glucose metabolism. 303 41

1. Measurements of the activities in rat liver of the four key enzymes involved in gluconeogenesis, i.e. pyruvate carboxylase (EC 6.4.1.1), phosphoenolpyruvate carboxykinase (EC 4.1.1.32), fructose 1,6-diphosphatase (EC 3.1.3.11) and glucose 6-phosphatase (EC 3.1.3.9), have been carried out, all four enzymes being measured in the same liver sample. Changes in activities resulting from starvation and diabetes have been studied. Changes in concentration (activity/unit wet weight of tissue) were compared with changes in the hepatic cellular content (activity/unit of DNA). 2. Each enzyme was found to increase in concentration during starvation for up to 3 days, but only glucose 6-phosphatase and phosphoenolpyruvate carboxykinase showed a significant rise in content. Fructose 1,6-diphosphatase appeared to decrease in content somewhat during the early stages of starvation. 3. There was a marked increase in the concentration of all four enzymes in non-starved rats made diabetic with alloxan or streptozotocin, for the most part similar responses being found for the two diabetogenic agents. On starvation, however, the enzyme contents in the diabetic animals tended to fall, often with streptozotocin-treated animals to values no greater than for the normal overnight-starved rat. Deprivation of food during the period after induction of diabetes with streptozotocin lessened the rise in enzyme activity. 4. The results are compared with other published values and factors such as substrate and activator concentrations likely to influence activity in vivo are considered. 5. Lack of correlation of change in fructose 1,6-diphosphatase with the other enzymes questions whether it should be included in any postulation of control of gluconeogenic enzymes by a single gene unit.
 ...
PMID:A comparison of the effects of diabetes induced with either alloxan or streptozotocin and of starvation on the activities in rat liver of the key enzymes of gluconeogenesis. 432 34

A radioimmunoassay for liver fructose-1,6-diphosphatase (D-fructose-1,6-bisphosphate 1-phosphohydrlase, EC 3.1.3.11) has been developed based on maintenance of its tetrameric structure and immunologic integrity after iodination by the Bolton-Hunter technique. The assay detected as little as 2 ng of standard enzyme. Nonspecific interference by tissue components did not occur. Enzyme concentration (mumol/1000 g tissue wet weight) was measured in tissue extracts of 49 rabbits subjected to a variety of conditions. In animals fed a 'balanced' diet containing 50--60% carbohydrate (by weight), the concentration in liver was 3.4 microM +/- 0.3. After fasts of 48, 72, or 96 h, the concentration in liver increased approximately 1.4-fold. A high-fat diet did not alter the concentration significantly but a high-protein diet caused an increase of 2.1-fold to 7.2 microM +/- 1.4. The greatest concentrations, 8.7 microM +/- 1.9, were observed in the livers of severely diabetic rabbits. The increase paralleled the increasing severity of diabetes and provides one explanation for the augmented gluconeogenesis which occurs in the diabetic state. Changes were less marked in kidney. The greatest apparent incrase, from 2.6 microM +/- 1.1 in the normal fed rabbit to 4.7 microM +/- 2.8, occurred in the severely diabetic animal. However, variation was sufficiently great in kidney to render apparent increases during fasting, protein feefing and diabetes statistically insignificant. For the most part changes in assayable activity followed changes in enzyme concentration except in the rabbits maintained on high-protein diets. In these, liver enzyme concentration increased by 2.4-fold whereas activity increased by only 1.3-fold, and the kidney enzyme concentration increased 1.3-fold whereas activity decreased by 20%.
 ...
PMID:Concentration of liver and kidney fructose-1,6-diphosphatase determined by specific radioimmunoassay. 615 42

A quantitative study of the effect of carnitine deficiency on expression of glycolytic and gluconeogenic enzymes was performed using juvenile visceral steatosis mice which are systemically deficient in carnitine. The amounts of glucokinase and L-type pyruvate kinase mRNA were reduced in homozygotes, compared to heterozygotes and normal controls at 2 and 8 weeks. Liver-type phosphofructokinase, however, did not differ significantly. The abundance of fructose 1,6-bisphosphatase mRNA was unchanged at 2 and 8 weeks. The level of phosphoenolpyruvate carboxykinase mRNA was increased slightly at 2 weeks, but not at 8 weeks. A part of these changes could not be explained by the plasma glucose or insulin level. Carnitine administration restored the mRNA of these enzymes to normal levels. These results suggest that carnitine deficiency affects the expression of these liver enzymes.
Diabetes Res Clin Pract 1996 May
PMID:Disordered expression of glycolytic and gluconeogenic liver enzymes of juvenile visceral steatosis mice with systemic carnitine deficiency. 885 99

The activity of phosphofructokinase-2, fructose, 1,6-bisphosphatase, glucokinase, and also the level of fructose 2,6-bisphosphate and glycogen were examined in the liver of normal, and streptozotocin-diabetic rats. It was shown that the activity of phosphofructokinase-2 was decreased in the liver of diabetic rats. Besides that the activity determined at pH 6.6 (the "active" or unphosphorylated enzyme form) was 3-fold reduced whereas the "total" enzyme activity as measured at pH 8.5 was lowered 1,7-fold. The phosphofructokinase-2 activity assay at two pH values allows to estimate a degree of phosphorylation of bifunctional enzyme which is markedly enhanced in diabetes. The fall of the bifunctional enzyme k in case activity is accompanied by the lowered fructose 2.6-bisphosphate level, increased fructose 1,6-bisphosphatase activity that in turn favours the liver tissue glycolysis inhibition and gluconeogenesis enhanced in diabetes.
 ...
PMID:[Functional characteristics of fructose-2,6-bisphosphate system in the liver during experimental streptozotocin diabetes]. 913 54

Type 2 diabetes is characterized by the inability of insulin to suppress glucose production in the liver and kidney. Insulin inhibits glucose production by indirect and direct mechanisms. The latter result in transcriptional suppression of key gluconeogenetic and glycogenolytic enzymes, phosphoenolpyruvate carboxykinase (Pepck) and glucose-6-phosphatase (G6p). The transcription factors required for this effect are incompletely characterized. We report that in glucogenetic kidney epithelial cells, Pepck and G6p expression are induced by dexamethasone (dex) and cAMP, but fail to be inhibited by insulin. The inability to respond to insulin is associated with reduced expression of the forkhead transcription factor Foxo1, a substrate of the Akt kinase that is inhibited by insulin through phosphorylation. Transduction of kidney cells with recombinant adenovirus encoding Foxo1 results in insulin inhibition of dex/cAMP-induced G6p expression. Moreover, expression of dominant negative Foxo1 mutant results in partial inhibition of dex/cAMP-induced G6p and Pepck expression in primary cultures of mouse hepatocyes and kidney LLC-PK1-FBPase(+) cells. These findings are consistent with the possibility that Foxo1 is involved in insulin regulation of glucose production by mediating the ability of insulin to decrease the glucocorticoid/cAMP response of G6p.
 ...
PMID:The forkhead transcription factor Foxo1 (Fkhr) confers insulin sensitivity onto glucose-6-phosphatase expression. 1169 81

The bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2) was recently identified as a new intracellular binding partner for glucokinase (GK). Therefore, we studied the importance of this interaction for the activity status of GK and glucose metabolism in insulin-producing cells by overexpression of the rat liver and pancreatic islet isoforms of PFK-2/FBPase-2. PFK-2/FBPase-2 overexpression in RINm5F-GK cells significantly increased the GK activity by 78% in cells expressing the islet isoform, by 130% in cells expressing the liver isoform, and by 116% in cells expressing a cAMP-insensitive liver S32A/H258A double mutant isoform. Only in cells overexpressing the wild-type liver PFK-2/FBPase-2 isoform was the increase of GK activity abolished by forskolin, apparently due to the regulatory site for phosphorylation by a cAMP-dependent protein kinase. In cells overexpressing any isoform of the PFK-2/FBPase-2, the increase of the GK enzyme activity was antagonized by treatment with anti-FBPase-2 antibody. Increasing the glucose concentration from 2 to 10 mmol/l had a significant stimulatory effect on the GK activity in RINm5F-GK cells overexpressing any isoform of PFK-2/FBPase-2. The interaction of GK with PFK-2/FBPase-2 takes place at glucose concentrations that are physiologically relevant for the activation of GK and the regulation of glucose-induced insulin secretion. This new mechanism of posttranslational GK regulation may also represent a new site for pharmacotherapeutic intervention in type 2 diabetes treatment.
Diabetes 2004 Apr
PMID:Interaction of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2) with glucokinase activates glucose phosphorylation and glucose metabolism in insulin-producing cells. 1504 17


1 2 3 4 Next >>